NEMANJA VIDIC has been ruled out for a minimum of eight weeks after surgery on his right knee as Alex Ferguson again faces a defensive crisis before a crucial period for Manchester United.

Of his recognised central defenders the manager has only Rio Ferdinand and Jonny Evans available, each of whom has doubts over his fitness. Vidic’s injury is to the same knee in which he damaged cruciate ligaments last December in a Champions League group game against Basel, causing him to miss the remainder of the season. This may raise fears regarding the long-term prognosis for the 30-year-old, with Vidic potentially being unavailable for more than the two months stated by United.

Vidic was not in the match-day squad for Sunday’s 2-1 win at Liverpool as a precautionary measure after he complained of tightness in the knee. A statement from the club said: “Nemanja Vidic has had a meniscus operation on his right knee and will be out for around eight weeks.

“Sir Alex, as a precautionary measure, rested Vidic at the weekend, after he complained of tightness in his knee; however, further medical investigation revealed the underlying problem. The central defender was operated on this week and will be sidelined for about eight weeks.”

That will rule him out of three Champions League matches and seven Premier League games, including those with Chelsea and Arsenal. United host Newcastle United in the League Cup tonight and Ferguson will almost certainly rest both Ferdinand and Evans in readiness for the Premier League visit of Tottenham Hotspur to Old Trafford on Saturday. Ferdinand has to manage a back condition and he left Anfield limping while Evans returned recently from injury and took a knock in the same game.

Phil Jones is also ruled out for the next eight weeks or so due to a knee injury, while Chris Smalling is yet to resume training after breaking a metatarsal.

If Ferdinand or Evans was also to become unavailable, Michael Carrick might be called upon to play in central defence as he did earlier this season. For the visit of Newcastle Ferguson could call up the inexperienced Michael Keane and Scott Wooton. Keane (19) has only one substitute appearance for United, while Wooton is yet to make his debut.

Of Keane, who is United's Reserve Player of the Year, Evans told mufc.com: "I've been really impressed with Michael when he's stepped up into training with us and I can see him getting a bit of a run-out if things go well."